Veterinary Topics

Cranial Cruciate Ligament Injury

Cranial Cruciate Ligament (CCL) rupture is one of the most common veterinary orthopedic injuries in dogs and causes intense pain, swelling, and lameness in one or both hind legs.

a white dog playing in park

Cranial Cruciate Ligament Injury

With an acute (sudden) rupture of the cranial cruciate ligament, many dogs will not place weight on the leg at all, sometimes leading owners to believe the leg has been broken or fractured. The cranial cruciate ligament is inside the knee, analogous to the ACL (anterior cruciate ligament) in humans, that prevents abnormal rotation and forward and backward motion of the bones of the knee relative to each other. In humans, these ligament tears are almost always traumatic – they occur when a soccer player twists a knee, a skier takes a bad fall, or a football player gets tackled.

In dogs, CCL injuries are usually not associated with significant trauma. In humans, the top of the shin bone is essentially flat, so we only put a strain on our cruciate ligament if we pivot our knee excessively or suffer a blow to the top of our shin. In dogs, however, the top of their shin bone has angled an average of 25 degrees. This means that whenever a dog is standing, walking, or putting weight on its leg, gravity wants the bottom of the thigh bone to slide back down that slope, like a car parked on a steep hill. This constant strain on the dog’s cruciate ligament predisposes them to a more chronic, gradual fraying of the ligament’s fibers that can lead to a complete tear over time.

Symptoms of CCL injury in veterinary medicine include:​

  • Gradual waxing and waning lameness, which may or may not improve with pain medications and rest
  • Non-weight bearing (with acute ruptures) that may gradually improve over time
  • Swelling at the knee joint that often is unnoticed by owners but may be visible to your veterinarian
  • Instability of the knee when tested by your veterinarian while your dog is sedated
  • A tendency to sit down with the affected knee lying straight and not bent in a flexed position​
  • Loss of muscle mass around the hip and thigh of that leg.

Because of this difference in bone structure and the resulting difference in why dogs tear their CCLs, the options for treating CCL injury in dogs are different than in humans. Surgery is almost always recommended to stop the abnormal motion in the knee, which leads to bone-on-bone grinding, the development of arthritis, and pain. There are multiple procedures available, and many different factors that go into determining which type of surgery is the best option for any individual pet. These can include your dog’s size, weight, activity level, bone structure, and gait pattern if they have any other orthopedic problems and if they have any other general health problems, for instance. ​​

Your veterinarian should perform a thorough orthopedic examination, including checking the stability of the knee. There may or may not be abnormal back-and-forth movement, but there will likely be pain evident to your veterinarian. X-rays help confirm the diagnosis and are used to look for other problems or injuries in the patient that should be considered when planning the next step.

  • What are the goals when we do corrective surgery for CCL injuries?
  • Minimize pain, improve comfort
  • Reduce arthritis overall in the long term
  • Return to the highest function possible
  • Improve the quality of life
  • Increase ability for activity, exercise, and mobility

Currently, the most common repairs are:

TPLO (Tibial Plateau Leveling Osteotomy)

For most dogs, TPLO is the best solution, as this repair has been shown to have the greatest return to function and the least amount of arthritis development later in life. Further, it is much more desirable in dogs with a severely sloped tibial plateau, such as often seen in large and giant breed dogs.

ligament x-ray
X-ray fracture repair

TTA (Tibial Tuberosity Advancement)

This procedure can be done for those dogs with a tibial plateau that is more flattened. It cannot be used in dogs that have sloped tibial plateaus. It is recommended that TPLO (shown above) be used instead.

X-ray of a TTA surgery in a dog.
X-Ray of knee of a dog

Veterinary patients with cruciate injuries, just like human patients, will do much better with physical rehabilitation therapy.

Rehabilitation therapy improves post-op recovery from many veterinary orthopedic surgeries, including cruciate ligament repairs such as TPLO, TTA, tightrope, and extra-capsular repairs. Click to learn more about Canine Rehabilitation Therapy.​

  • Post-op recovery from orthopedic surgery and soft tissue surgery
  • Athletic and sports conditioning
  • Injury prevention
  • Weight loss programs
  • Pain management
  • Arthritis management
  • Decreased mobility
  • Improving quality of life